Re: Should consider materializing the cheapest inner path in consider_parallel_nestloop()
| От | Tender Wang |
|---|---|
| Тема | Re: Should consider materializing the cheapest inner path in consider_parallel_nestloop() |
| Дата | |
| Msg-id | CAHewXNnSvL1M76-NKyns3F9uK1RvEBZMX8z3bQ2itpLn7ZjTfQ@mail.gmail.com обсуждение исходный текст |
| Ответ на | RE: Should consider materializing the cheapest inner path in consider_parallel_nestloop() ("Fujii.Yuki@df.MitsubishiElectric.co.jp" <Fujii.Yuki@df.MitsubishiElectric.co.jp>) |
| Ответы |
Re: Should consider materializing the cheapest inner path in consider_parallel_nestloop()
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| Список | pgsql-hackers |
Fujii.Yuki@df.MitsubishiElectric.co.jp <Fujii.Yuki@df.mitsubishielectric.co.jp> 于2024年6月5日周三 09:26写道：
Hi. Tender.
Thank you for modification.
> From: Tender Wang <tndrwang@gmail.com>
> Sent: Tuesday, June 4, 2024 7:51 PM
> Please add more tests. Especially please add some negative tests;
> current patch checks that it is safe to apply materialization. It would
> be helpful to add tests checking that materialization is not applied
> in both checked cases:
> 1. when inner join path is not parallel safe
> 2. when matpath is not parallel safe
>
>
>
> I added a test case that inner rel is not parallel safe. Actually,
> matpath will not create if inner rel is not parallel safe. So I didn't add test case for the second scenario.
Is there case in which matpath is not parallel safe and inner rel is parallel safe?
If right, I think that it would be suitable to add a negative test in a such case.
I looked through create_xxx_path(), and I found that almost path.parallel_safe is assigned from RelOptiInfo.consider_parallel.
Some pathes take subpath->parallel_safe into account(e.g. Material path). In most cases, Material is parallel_safe if rel is parallel
safe. Now I haven't come up a query plan that material is un parallel-safe but rel is parallel-safe.
Sincerely yours,
Yuuki Fujii
--
Yuuki Fujii
Information Technology R&D Center Mitsubishi Electric Corporation
Tender Wang
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